Hi I had the problem also in 3D it was sparadic at first and worcened with time. I found that the problem realy was coused by the fact my hard drive needed defraging. once I did that the problem disapeared and I havent seen it sence in eather my 3D or 4 versions. and yes I still use 3 when laying out large sceens as it is smaller and frees a bit more ram for layout work and not dorment bryce functions Im not useing at the time. hope this helps Later Vel